Hinges for orthopedic braces having an adjustable rotation range in the extension and flexion direction are well known in the art. For example, U.S. Pat. No. 4,481,941 to Rolfes discloses a hinge having a pair of threaded screws, each being selectively threadably securable in one of a plurality of correspondingly threaded holes formed in the body of the hinge. The hinge rotation range is a function of screw placement insofar as securing a screw in a given hole determines a particular hinge rotation limit. The hinge rotation range is adjusted by changing the hinge rotation limit, which requires removal of the screw from its respective hole and placement of the screw in an alternate hole. However, It has been found that the task of adjusting the hinge rotation range can require a significant degree of dexterity to maneuver the relatively small screws into and out of the threaded holes. Furthermore, the screws are susceptible to being misplaced or lost during this task.
An alternate adjustable hinge disclosed by U.S. Pat. No. 401,933 to De Camp, substitutes pins for threaded screws as a means for setting the hinge rotation limit. The smooth surface of the pins enables them to slide in and out of the holes formed in the body of the hinge. The pins are secured in the holes by a leaf spring attached to each pin which biases the pin into its respective hole in a direction parallel to the axis of hinge rotation. Repositioning the pins of De Camp requires less dexterity than repositioning the screws of Rolfes. Nevertheless, De Camp still requires the user to pry the leaf spring away from the hinge body and remove the pin from the hole when adjusting the hinge rotation range. Accordingly, hinges having an improved adjustment mechanism were developed and disclosed in U.S. Pat. Nos. 5,672,152 and 5,827,208 to Mason et al.
The hinges of Mason et al. are relatively easy to set at a desired rotation limit in the extension or flexion direction and also have the desirable capability of being selectively lockable against rotation altogether. In accordance with one embodiment, the hinge of Mason et al. includes a plurality of rotation limiting notches and a locking notch formed in the peripheral edge of the hinge. A rotation limiting assembly is provided which is selectively positionable in one of the rotation limiting notches to define a hinge rotation limit. Alternatively, the rotation limiting assembly is selectively positionable in the locking notch to lock the hinge against rotation. The hinge also includes a biasing assembly which biases the rotation limiting assembly in a radially inward direction perpendicular to the axis of hinge rotation, thereby retaining the rotation limiting assembly in its selected rotation limiting position or locked position. The biasing assembly, however, enables elastic radial displacement of the rotation limiting assembly in a radially outward direction when a radially outward displacement force is externally applied thereto. The biasing assembly returns the rotation limiting assembly to a selected rotation limiting or locked position when the displacement force is withdrawn.
Although the above-recited hinge of Mason et al. is a substantial improvement over the hinges of De Camp and Rolfes, it is noted that the hinge of Mason et al. utilizes the same rotation limiting assembly for two different functions. In particular, the rotation limiting assembly is used to set a desired hinge rotation limit as well as to selectively lock the hinge against rotation altogether. Therefore, it is necessary to remove the rotation limiting assembly from its selected rotation limiting position and place the rotation limiting assembly in the locked position when it is desired to lock the hinge against rotation. When it is desired to enable rotation by unlocking the hinge, the rotation limiting assembly is removed from the locked position and returned to its selected rotation limiting position. This sequence of steps inherently increases the risk of erroneously resetting the hinge rotation limit when the rotation limiting assembly is returned to the rotation limiting position if the user has forgotten or improperly locates the prior prescribed hinge rotation limit. Therefore, a need exists for a hinge for an orthopedic brace having an adjustable rotation range, further wherein the hinge is selective between a locked mode and an unlocked mode of operation without disrupting the selected hinge rotation limits.
Accordingly, it is an generally an object of the present invention to provide a hinge for an orthopedic brace, which has an adjustable rotation range, and which has a locked and an unlocked mode of operation. More particularly, it is an object of the present invention to provide such a hinge having a rotation limiting mechanism, which selectively enables adjustment of the hinge rotation range, and also having a locking mechanism, which selectively enables locking the hinge against rotation altogether. It is still another object of the present invention to provide such a hinge, wherein the locking mechanism can be transitioned between the locked and unlocked modes without altering the rotation limits of the rotation limiting mechanism. These objects and others are accomplished in accordance with the invention described hereafter.